Aramid-fibre-reinforced polymer composites

AFRP Aramid-fibre-reinforced polymer composites... 

Klein N, Marom G, Wachtel E, Microstructure of nylon 6,6 transcrystalline layers in earbon and aramid fibre reinforced composites. Polymer, 37(24), 5493-5498, 1996. 

Correa and co-workers [a.272] studied the thermal behaviour of short-fibre-reinforced PU composites by DSC and TG techniques and reported that the thermal resistance of aramid-fibre-reinforced composites was greater than that of carbon-fibre-reinforced composites or the pure matrix polymer. The DTG results are presented in Figure 31. 

Traditional fibres used as reinforcement in polymer composites are generally either polymers or ceramics the polymer aramids, glass, carbon, boron, aluminium oxide and silicon carbide. Carbon is a high-performance fibre material that is the most commonly used reinforcement in advanced polymer-matrix composites. Glass fibre is readily available and may be fabricated into a glass-reinforced plastic economically using a wide variety of composite-manufacturing techniques. 

The chapter demonstrates that in spite of the incompatibility between hydrophilic natural fibres and hydrophobic polymeric matrices, the properties of natural fibre composites can be enhanced through chemical modifications. The chemical treatments have therefore played a key role in the increased applications of natural fibre composites in the automotive sector. Recent work has also shown that if some of the drawbacks of natural fibres can be adequately addressed, these materials can easily replace glass fibres in many applications. The chapter has also shown that there have been attempts to use natural fibre composites in structural applications, an area which has been hitherto the reserve of synthetic fibres like glass and aramid. The use of polymer nanocomposites in applications of natural fibre-reinforced composites, though at infancy, may provide means to address these efficiencies. Evidence-based life-cycle assessment of natural fibre-reinforced composites is required to build confidence in the green composites applications in automotive sector. 

Reinforcements, with the exception of carbon and SiC fibres, are electrical insulators, as are all polymer matrices whether thermoset or thermoplastic. Hence composites based on glass or aramid fibres can be used as insulators or in situations where transparency to electromagnetic radiation is required (e.g. D-glass). Materials based on carbon fibres may be used for electrical screening. 

As a result of their outstanding physical and mechanical properties, aromatic polyamides are attractive materials for use in high-performance structural applications 853072 833611 820253, including aircraft components or fire protection garments, as constituents of both traditional, i.e., fibre-reinforced composites 774110 762844, and molecular composites. One of these applications takes advantage of their thermal stability 881232 825031 763791 755849 and allows the manufacturing of heat-resistant materials for fire protection 713906. In a different context, aromatic polyamides (aramid fibres) have been proposed in the past few years as precursors of activated carbon materials with distinctive adsorbent properties (thermally stable molecular sieves). Aramid fibres, e.g., poly(w-phenylene isophthalamide), poly(p-phenylene terephthalamide) 709654, etc., are a class of synthetic polymers that possess excellent thermal and oxidative stability, good flame resistance, and superior mechanical and dielectric behaviour. 

Short fibres of glass, rayon, aramid, asbestos and cellulose as reinforcing fillers, have been broadly used in rubber industries due to their high modulus, high strength and low creep. In recent years especially, natural fibres such as jute fibre, cellulose fibre, " coir fibre," " sisal fibre," " etc. have been also widely used in NR composites because they are enviromnental friendly, cheap, abundant and renewable. However, natural fibres also have some disadvantages such as moisture absorption, quality variations, low thermal stability and poor compatibility with the hydrophobic polymer matrix. 

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